Selective Laser Scanner Stereo Vision for Parallax-Free Feature Scanning

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Solution Overview

Problem

Existing selective laser scanners face challenges in accurately converting image coordinates from a camera to scanner coordinates due to parallax errors caused by the camera being offset from the measurement beam, leading to difficulties in directing the measurement beam to a point of interest and requiring manual feature selection and scan perimeter definition.

Innovation Solution

A selective laser scanner equipped with two cameras arranged offset from the target axis, with overlapping fields of view, uses stereo vision to calculate depth maps and resolve parallax through triangulation, enabling automatic feature detection and scan area definition, and provides a virtual image from the scanner's viewpoint for precise coordinate transformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the camera is mounted offset from the measurement beam to provide a live view, then the user can see the scene and select features, but parallax error occurs between the camera axis and laser target axis making coordinate transformation difficult

Engineering Contradiction:

Improvefeature selection capabilityVSAvoidcoordinate transformation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a coordinate transformation unit that acts as an intermediary between the camera coordinate system and the laser scanner coordinate system. This unit performs mathematical transformation using calibration data to convert coordinates from the offset camera view to the laser measurement coordinates, thereby resolving the parallax error problem while maintaining both the live view capability and measurement accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by using calibration data that defines the spatial relationship between the camera and laser target axis. Through parameter transformation matrices and coordinate system adjustments, the system converts image coordinates to scanner coordinates accurately despite the physical offset, eliminating parallax effects in the coordinate transformation process

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If manual feature selection and scan perimeter definition is used, then the system can scan specific areas, but user interaction time and scan setup time increase

Engineering Contradiction:

Improveselective scanning capabilityVSAvoidscan setup time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements self-service through automated feature detection algorithms that automatically identify and select features of interest in the camera view, and automatically define scan perimeters based on detected features. This eliminates the need for manual user interaction for feature selection and scan area definition, significantly reducing setup time while maintaining selective scanning capability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces the manual mechanical interaction (user clicking and drawing on the display) with automated computational processes. Image processing algorithms and pattern recognition systems automatically detect features and define scan areas, substituting human操作 with automated software-based solutions that are both faster and more consistent

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution allows for automatic and precise correlation between the laser target axis and visual camera axis, reducing user interaction and scan time by eliminating parallax errors and enabling accurate, automated feature recognition and scan strategy determination.

Implementation Method 1

a first camera (2) and a second camera (3), in each case arranged offset from the target axis (12) in a fixed positional arrangement with respect to each other

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

uses stereo vision to calculate depth maps and resolve parallax through triangulation

Methodology Applied

Scientific EffectTriangulation: Parallax

Implementation Method 3

configured to transmit a distance measuring beam defining a target axis

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 4

a distance measuring unit configured to carry out a distance measurement by means of the distance measuring beam

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS12492894B2Laser scanner with stereo camera vision for improved selective feature scanning

Publication Date: 2025.12.09 LEICA GEOSYSTEMS AG

AI summary

A selective laser scanner, comprising a target component which can be rotated about two rotation axes and is configured to transmit a distance measuring beam defining a target axis. The selective laser scanner further comprises a distance measuring unit configured to carry out distance measurements by means of the distance measuring beam on cooperative targets or on diffusely scattering targets. The selective laser scanner is equipped with a plurality of overview cameras arranged on the target component offset from the target axis in a fixed positional arrangement with respect to each other having field of views which at least partly overlap each other. The selective laser scanner further comprises a display for displaying an environment image provided by imaging data of at least one of the cameras as well as automatic feature and area detections.